[Exhibitman]

The problem isn't just one thing. In no particular order:

--Rarity vs. obscurity: The Charleston v. Clemente example is extreme but there are plenty of examples among the Clemente cards that are rarer than a 1955 Topps. The early Kahn's cards and the 1962 Pittsburgh Exhibit come right to mind. But those are relatively obscure cards and people don't chase them except as needed for a registry quest. A Topps RC will slaughter them at auction despite the relative rarity. Rare is fun but when it shades into obscurity, you are SOL.

--Set significance: 1955 Topps, one of the Topps Golden Age sets. 52-56 Topps is about as high profile as T206 and 1933 Goudey. These are the classics, the 'Yellow Submarine' of cards. When I saw Ringo and his allstar band some years ago, he prefaced YS with a speech about how everyone knows this song from grandmums to their grandkids. Same idea in card-world.

--Lack of population: call this the collectability factor. People just don't value what they can't hope to own. I've never gotten into NL collecting because I know that I will never own a Cuban Charleston card, a vintage Josh Gibson RPPC, a Punch card, etc., unless one falls into my lap. I have no deep interest in what I cannot ever collect. Casual interest as a curious collector, sure, desire to know what it is in case I stumble across one in a junk shop, absolutely, but not more than that. But a 1955 Clemente, I have one, and I could conceivably find a nicer one in some collection I purchase.